Optical systems are widely used in communications applications to facilitate the exchange of information such as voice and data over fiber cable, which may be fabricated from glass or any other suitable composite material. Both telephony and Internet-based systems exploit the wide bandwidth and large data capacity that optical systems provide. Additionally, as compared to conventional wired systems, optical networks are easily maintained and repaired.
Conventional optical systems include a transmitter having a distributed feedback (DFB) laser that operates at a wavelength at or near one of the wavelengths specified by the International Telecommunications Union (ITU). The DFB laser operates at an ITU specified wavelength within a particular temperature range. Outside the operating temperature range of the DFB laser, the DFB laser becomes detuned and no longer lases at the appropriate wavelength.
The optical transmitter also includes a modulator, such as an electro-absorption (EA) modulator that imparts information onto the emitted optical energy before the optical energy is coupled to the fiber optic cable. Like the DFB laser, the EA modulator has an optimal operating temperature range and wavelength at which the chirp, which represents the maximum distance that information may be transmitted from the EA modulator, was optimized.
For acceptable operation of the previously-described optical transmitter, the operating temperature of the EA modulator and the DFB laser must be matched. Failure to match the operating temperatures of these components leads either to a transmitter that lases at the proper frequency and has poor chirp performance or to a transmitter that has acceptable chirp performance, but lases at an incorrect wavelength or that drifts between wavelengths. As will be readily appreciated by those having ordinary skill in the art, the production yield of optical transmitters is very low when having to match the operating temperature ranges of two different components.